Investigators for the U.S. Department of Energy reported Friday that a second nuclear weapons lab — University of California-operated Los Alamos Lab in New Mexico — has been “regularly” recording conversations on its security phone lines without notification to workers.

Last year, the Energy Department’s inspector general found the same thing at Sandia National Laboratories in New Mexico. Both labs had disabled a notification feature on their phone recording systems so workers never heard beeps to signal they were being recorded.

Federal regulations and laws in many states require mutual consent for the recording of phone conversation, and Energy Department regulations say the beeping notification

is part of that consent.

Both labs now have restored the notification.

In a report released Friday, the Energy Department’s inspector general said Los Alamos security managers have been archiving the recorded conversations. In some cases, managers received transcripts of those conversations and at Sandia, according to the inspector general, had used them in disciplinary proceedings.

Los Alamos officials said the disabling of the beeping notification was an inadvertent “technical glitch.”

Lab spokesman Jim Fallon said a worker was upgrading the recording system and unknowingly “deleted” the notification tone for certain telephone lines. Those lines, according to the inspector general, included the lab’s Central Alarm Station but also the desk phones for security-force shift captains and scheduling supervisors.

There was, said Fallon, “no nefarious intent, and clearly we respect the privacy of our staff and also the need to meet DOE emergency response orders.”

The inspector general’s report quoted a Los Alamos official as saying the notification was disabled because “portions of conversations were being overwhelmed” by the beeping, sometimes interfering with the receipt of critical information.

Officials at Lawrence Livermore and Sandia labs in California said they always keep parties on their security phones notified that they are being recorded.

Violent police encounters in California last year led to the deaths of 157 people and six officers, the state attorney general’s office said Thursday in a report that provides the first statewide tally on police use-of-force incidents.

At 6:03 p.m. Wednesday, police responded to reports of the robbery at the facility, 2301 Bancroft way, and learned that a man who snuck into the facility and began prowling through the building, taking cell phones and wallets from victims.

Investigators’ efforts to solve the case led to the arrests of Pablo Mendoza, 25, of Hayward, Brandon Follings, 26, of Oakland and Valeria Boden, 26, of Alameda, the Alameda County Sheriff’s Office said Thursday.